Colour blindness

Protanopia; deuteranopia; tritanopia; achromatopsia

People who are affected by colour blindness are unable to distinguish between different hues of certain colours.

The most commonly affected distinction is between red and green, although problems can also occur with the blue and yellow wavelengths, as well as total colour blindness.

Advice for using this method

  • Don't rely solely on colour to highlight something, such as red text. Add another visual cue such as boldness or underline.
  • Avoid placing red and green together.
  • Choose colours with awareness. ColorBrewer 2.0 is a resource that can help in making accessible colour decisions. ​ 
  • Check your documents for visual accessibility before the final draft. 
    • Print in greyscale and make sure the document does not rely on colour for clarity.
    • Use a tool like Vischeck to see how your images look under different forms of colour blindness.


'Colour blindness' is referenced in: